Electrical connector



United States Patent 3,377,613 ELECTRICAL CONNECTOR Andrew M. Archer, Rincon Seamans Unit,

San Francisco, Calif. 94119 Filed Feb. 15, 1966, Ser. No. 527,713 2 Claims. (Cl. 339-154) ABSTRACT OF THE DISCLOSURE A device for converting electrical connector plugs of conventional design into safety plugs comprising a housing of insulating material having contact blade-receiving sockets on one side thereof, connector blades protruding from another side thereof, covers of insulating material enveloping portions of said blades adjacent said housing, and means within said housing for locking contact blades inserted into said sockets in position within the housing and establishing conductive connection between such inserted contact blades and the connector blades of the device.

The present invention relates to electrical plug and socket connectors. In devices of this type the plug carries usually a number of conductive blades which are pushed into slot-shaped receptacles of a socket that is provided with contact elements which are permanently connected to a source of electric power. When these blades are inserted into, or withdrawn from, the slots of the socket, and especially when they are not fully inserted into the slots of the socket, they present a grave danger to grownups as well as children because they may be touched inadvertently while carrying current, and may thus impart a severe shock to, and even cause the death of the person whose fingers come into contact with them.

It is an object of the present invention to provide a device by means of which the dangerous connector plugs of conventional design may be rendered safe.

More specifically it is an object of the invention to provide a device which may be applied to connector plugs of conventional design to convert them permanently into safety plugs.

These and other objects of my invention will be apparent from the following description of the accompanying drawing which illustrates a preferred embodiment thereof and wherein:

FIGURE 1 is a fragmentary side elevation, partly in section, of a combined socket and plug arrangement embodying my invention, and shows a socket into which its connector blades are inserted and a plug of conventional design that has been connected to its socket portion.

FIGURE 2 is a front view of the arrangement shown in FIGURE 1.

FIGURE 3 is an enlarged fragmentary section through the socket portion of the arrangement illustrated in FIGURES 1 and 2;

'FIGURE 4 is a side elevation of one of the contact blades of the arrangement of my invention, and

FIGURE 5 is a plan view of the blade shown in FIG- URE 4.

I provide the portions of the contact blades of a connector plug adjacent the body of the plug with sheathes or covers of an insulating material so that only their ends are left bare. Hence, once the unprotected ends of the blades have made contact with the live contacts of an electric socket, the portions of incompletely inserted connector blades that are accessible to, and may accidentally be contacted by the fingers of the person handling the plug, are insulated and cannot do any harm.

Since most electric appliances now in use are provided with potentially dangerous connector plugs, my invention 3,377,613 Patented Apr. 9, 1968 provides a combination of the above described safety plug with an electric socket in which the blades of a conventional electric connector plug may be inserted and wherein, once inserted, they will be permanently locked so that they can no longer be withdrawn. Hence, a conventional connector plug once its blades have been inserted into the socket of the combined socket and safety plug arrangement of my invention, is rendered safe and may be handled with the same degree of safety as an ordinary safety plug.

In the exemplary embodiment of the invention illustrated in the accompanying drawing, the device of my invention comprises an L-shaped body or housing 10 of a suitable plastic insulating material. Two parallel contact blades 12a and 12b of electrically conductive material, such as bronze, project from end 14 of the housing 10 (FIGURES 1 and 2). These projecting ends may be inserted into the slot-shaped receptacles 15 of a socket 16 of conventional design to engage the contact springs 18 that are usually provided in such sockets (FIGURE 1) .and which in turn are permanently connected to a source of electric currentwhen the sockets are installed. The projecting portions of the blades are partially covered by a thin sheath or coat 20 of insulating material (FIGURES 1, 4 and 5) so that only their tips or end portions 22 remain bare to establish the necessary conductive contact with the contact springs 18 of socket 16 when the blades are inserted into the socket. To prevent the covers of insulating material 20 from interfering with proper insertion of the blades into the socket, the covered portions 24 of the blades should preferably be of lesser depth and thickness than the bare terminal portions of the blades, as best shown in FIGURES 4 and 5. For the same reason I prefer to use as material for the sheathes or covers 20 a smooth substance such as the substance known as Tefion. Moreover, the front edges of the sheath or covers 20 and the rear edges of the tip or terminal portions 22 of the blades at the juncture between the covers and the bare terminal portions of the blades should preferably be beveled as indicated at 26 and 27 in FIGURES 5 and 6.

The covers of insulating material may be applied to the blades 12 in any suitable manner such as by painting them with, or dipping them into a bath of, insulating material that solidifies upon drying or upon exposure to heat. Alternatively sheathes or sleeves of insulating material of a somewhat elastic nature may be pulled over the ends of the blades 12 until they are properly seated over the reduced areas 24 of the blades.

When a plug with contact blades constructed as above described is incompletely inserted into a socket 16, yet makes conductive contact with the spring blades 18 of the socket, the areas of the blades that are accessible to the operators finger are always properly insulated so that no harm can come to the user of the plug or to a child that may playfully handle the plug.

The embodiment of the invention illustrated in the accompanying drawings is constructed to provide means for rendering electrical appliances safe, that are provided with plugs of conventional design. For this purpose a pair of contact blade receiving slots 30a and 30b is provided in the opposite end 32 of the housing 10, and held in said housing adjacent said slots are spring blades 34a and 34b (FIGURES 1 and 3) which are conductively connected within the housing 10 to the rear ends of the contact blades 12a and 12b, respectively in the plug portion 14 of the device, such as by means of suitable leads 35. At points inwardly removed from the entrance of the slots 30a and 30b said spring blades form a bead or kink 36 that projects into the path of contact blades 38a and 38b (FIGURES 1, 2 and 3) which may be inserted into the slots 30a and 3%, respectively. The contact blades of most plugs of conventional design contain holes 40 which are usually located near the free ends of said blades such as shown in FIGURES 1, 3 and 4.' When such blades are inserted into the slots 30a and 30b in the socket portion 32 of the device of the invention, and their end edges come against the beads or kinks 36 of the spring blades 34, said spring blades are cammed laterally out of the way of the advancing contact blades 38 until the apertured areas 40 of said blades negotiate said kinks. At this moment the kinks 36 snap into the apertures 40, due to the resiliency of the spring blades, and securely lock the blades 38 of an applied plug 44 in their inserted positions. The plug 44, therefore, can no longer be withdrawn from the socket portion 32 of the device of my invention, and the safety plug portion 14 of the arrangement of the invention becomes now in fact the plug of the appliance. Thus, an appliance originally provided with a potentially dangerous connector plug is now as safe as if it had originally been provided with the safety plug of my invention.

As mentioned hereinbefore the embodiment of the invention illustrated in the accompanying drawing has an L-shaped housing wherein the two bars 14 and 32 of the L which are disposed at right angles to each other, form the plug and socket portions, respectively, of the device. It will be obvious that the housing may have the form of a straight bar with its plug and socket portions being provided in the opposite ends of the bar. However, I prefer an L-shaped housing or body of the type illustrated in FIGURES 1 and 2 for reasons of compactness. If the housing of the device had the form of a straight bar, it would extend too far out from the wall where the electric socket is installed, and might thus constitute a hazard or might easily be broken off.

While I have described my invention with the aid of a particular embodiment thereof, it will be understood that the invention is not limited to the specific constructional details shown and described by way of example which may be departed from without departing from the spirit and scope of the invention.

Iclairn:

1. Arrangement for converting electrical connector plugs of conventional design into safety plugs comprising a housing of insulating material having a contact blade receiving receptacle on one side thereof, a connector blade protruding from another side thereof, a cover of insulating material enveloping a portion of said protruding connector blade adjacent said housing, and means within said receptable for establishing conductive connection between a contact blade inserted into said receptable and said connector blade and for permanently locking an inserted contact blade in position within said receptacle.

2. Arrangement according to claim 1 wherein said connection establishing and locking means is a spring blade arranged within said receptacle adjacent the path of entrance of an inserted contact blade and having a lateral kink arranged to extend into said path of entrance and adapted to snapinto an aperture in the inserted contact blade when conductive contact between said inserted contact blade and said connector blade has been established.

References Cited UNITED STATES PATENTS 2,226,148 12/1940 Taylor 339-491 2,537,370 1/1951 Parnes 339-195 2,664,734 1/1954 McEneaney 339-91 2,732,531 1/1956 Janowiec 33991 X 2,761,113 8/1956 Spencer et al. 339-157 X FOREIGN PATENTS 429,219 5/ 1935 Great Britain. 1,131,291 2/1960 Germany.

MARVIN'A. CHAMPION, Primary Examiner.

J. R. MOSES, Assistant Examiner. 

